The present invention relates to improvements in apparatus for transporting and otherwise treating sheets of paper or the like. More particularly, the invention relates to improvements in methods of and in apparatus for converting a file of successive non-overlapping sheets into a stream of sheets wherein the leading portion or section of each next-following sheet overlaps with the trailing portion of the immediately preceding sheet.
Apparatus of the above outlined character can be uti- lized with advantage in paper processing plants wherein large panels are severed lengthwise and/or crosswise to yield sheets of a desired size and shape, and wherein the sheets are thereupon stacked into accumulations (e.g., those known as reams) which contain predetermined numbers of fully overlapping sheets. The thus obtained accumulations are thereupon wrapped and crated or boxed prior to shipment into storage or to the purchasers.
In order to properly stack successive sheets of a file of rapidly advancing sheets, it is necessary to re- duce the speed of successive oncoming sheets in a selected portion of the path for the file so that the trailing section of the braked sheet can be caused to predictably overlap with the leading section of the immediately following sheet. This is accomplished by diverting the trailing section of the braked sheet from the path of the leading section of the immediately following sheet (i.e., of the sheet which is about to be braked) and/or vice versa. As a rule, the trailing section of the freshly braked sheet is flexed downwardly so that the leading section of the next-following sheet can slide over and thus overlie the downwardly flexed trailing section of the immediately preceding sheet. The thus obtained stream of partially overlapping sheets is transported lengthwise to a stacking station where the sheets are gathered into reams or other suitable accumulations or piles.
An apparatus of the just described character is disclosed in German patent No. 26 01 081 A1. The patented apparatus employs a first endless belt conveyor for advancement of successive sheets of the file to a converting station where the oncoming sheets are braked to be properly overlapped by the leading sections of the next-following sheets, a second endless belt conveyor which transports the stream of partially overlapping sheets from the converting station, and a third conveyor which overlies portions of the first and second conveyors at the converting station to thus establish predictable paths for advancement of non-overlapping sheets to and for advancement of partially overlapping sheets from such station. The patented apparatus further comprises a suction-operated deflecting device which causes the trailing sections of successive sheets at the converting station to flex downwardly and to thus provide room for unimpeded advancement of the leading section of the next-following sheet over the thus flexed trailing section. The flow of air which is generated by the suction-operated deflecting device can further serve to flex the leading sections of successive oncoming sheets of the file upwardly and to thus further reduce the likelihood of collision between the trailing sections of preceding sheets and the leading sections of the immediately following sheets.
A drawback of the just described patented apparatus is that its operation is reliable, predictable and econo- mical under certain circumstances, and that such apparatus cannot automatically and/or reliably alter its mode of operation when an alteration is desirable, required or absolutely necessary. This can entail the turning out of large numbers of rejects and can affect the output or outputs of one or more machines which receives or receive partially overlapping sheets from the patented apparatus and/or which supply sheets to such apparatus.
An object of the invention is to provide an apparatus which can convert a file of successive sheets into a stream of partially overlapping sheets with a degree of reliability which is higher than that of heretofore known apparatus.
Another object of the invention is to provide an apparatus of the above outlined character which is more versatile than conventional apparatus.
A further object of the invention is to provide a novel and improved method of ensuring that the above out-lined apparatus can operate in a predictable and optimum manner under circumstances which are likely to change for any one of a host of different related and/or unrelated reasons.
An additional object of the invention is to provide the above outlined apparatus with novel and improved means for controlling the treatment of trailing sections of preceding sheets and/or of leading sections of next-following sheets at the station where such sheets are caused to partially overlap with each other.
Still another object of the invention is to provide an apparatus the operation of which is more economical than that of presently known and utilized apparatus because it turns out fewer rejects than such presently known apparatus.
A further object of the invention is to provide an apparatus which can be utilized as a superior substitute for presently used apparatus serving to convert a file of successive sheets into a stream of partially overlapping sheets.
Another object of the invention is to provide an apparatus which can carry out necessary adjustments in response to departures of the characteristics of sheets from anticipated characteristics and/or in response to changes in the mode of operation of the sheet advancing, braking and/or flexing means.
An additional object of the invention is to provide the above outlined apparatus with novel and improved means for reliably maintaining non-overlapping as well as partially overlapping sheets in their respective paths toward and away from the converting station.
Still another object of the invention is to provide the improved apparatus with novel and improved means for regulating the force which is being applied at the converting station in order to avoid collision between the trailing sections of successive last sheets of the stream and the leading sections of successive foremost sheets of the file of non-overlapping sheets.
A further object of the invention is to provide a production line which employs one or more apparatus of the above outlined character and the mode of operation of which can influence the operation of the apparatus in a sense to reduce the number of rejects (such as stacks containing improperly stacked sheets) and/or to increase the output.
One feature of the present invention resides in the provision of an apparatus for delivering successive flexible sheets of a file of non-overlapping sheets in a pre-determined direction along a first path wherein a trailing portion or section of each preceding sheet is located ahead of a leading portion or section of the next-following sheet to a file-converting station (also known as scalloping station) where the trailing sections of successive preceding sheets of the file are caused to overlap with the leading sections of the respective next-following sheets. The improved apparatus comprises means for supplying successive sheets of the file in the predetermined direction along the first path to the converting station at a first speed, means for removing successive sheets of the file from the converting station along a second path at a different second speed which is less than the first speed so that the leading sections of the sheets arriving at the converting station overlap with the trailing sections of the respective preceding sheets, means for deflecting at the converting stationxe2x80x94with a variable forcexe2x80x94at least one of each pair of sections including the trailing section of a preceding sheet and the leading section of the respective next-following sheet so that the sections of such pairs of sections can overlap each other, as a result of the difference between the first and second speeds, and means for varying the aforementioned variable force as a function of at least one of a plurality of variable parameters. Such variable parameters can include the aforementioned first and second speeds, the flexibility of sheets, the temperature in the first path and/or at the converting station, the moisture content of the sheets, the specific weight of the sheets, the dimensions of the leading and/or trailing sections of the sheets, and the orientation of the first and second paths relative to each other.
At least some of the sheets can include or constitute paper sheets.
The deflecting means can include means for directing the variable force at a right angle or at an oblique angle to the direction of movement of sheets along at least one of the first and second paths, or even in parallelism with the first or second path.
It is often preferred to provide the deflecting means with means for directing the aforementioned force against the trailing sections of the pairs of sections so that the thus deflected trailing sections of successive sheets are moved away from the path of the respective (immediately following) leading sections.
If each of the sheets comprises two or more thinner sheets or leaves, one of the aforementioned parameters can include the number of leaves in a sheet
One of the parameters can include the thickness of the sheets.
The means for varying the aforementioned force can include means for varying the magnitude of such force (e.g., as contrasted with varying the direction of the force or the duration of application of the force).
For example, the means for varying the force can include at least one memory for storage of information pertaining to at least one of the variable parameters; for example, the information which is stored in the at least one memory can include characteristic curves and/or functions. The stored characteristic curves can have gradually and/or abruptly changing portions.
The variable force can be selected in such a way that it includes an upper and/or a lower threshold value.
If the at least one parameter is one of the first and second speeds, the force can vary at least substantially proportionally with variations of the one speed; the force can increase in response to an increase of the one speed and decrease in response to a reduction of the one speed. The variable force can decrease to zero when the one speed decreases to a predetermined minimum value, and such force can remain constant at a predetermined maximum value when the one speed reaches or rises above a preselected speed.
The deflecting means can comprise at least one suction generating device, e.g., a blower or an ejector. More specifically, the at least one suction generating device can comprise air stream generating means and means for directing the generated air stream against one side of the trailing section of each of the aforementioned pairs of sections to thus establish a low-pressure zone which causes or entails a deflection of the trailing section from the path of the oncoming leading section of the respective pair of sections. The air stream generating means is or can constitute a variable-output air stream generating means, and the means for varying the force can include means for varying the output of the air stream generating means.
The air stream generating means can be spaced apart from the directing means, and the suction generating device can further comprise a conduit which connects the air stream generating means with the directing means; the force varying means can comprise an adjustable valve in the conduit and means for adjusting the valve as a function of the at least one parameter to thus alter the rate of air flow from the suction generating device to the directing means. The valve adjusting means can comprise a prime mover which is adjustable in dependency upon variations of the at least one parameter.
The air stream generating means can comprise an air compressor, and the at least one suction generating device of such apparatus can further comprise means for limiting the pressure of air which is being supplied by the air compressor.
The apparatus can further comprise a conveyor (e.g., an endless belt conveyor) which cooperates with at least one of the aforementioned sheet supplying and sheet removing means to define the respective path. Such apparatus can further comprise means for adjusting the conveyor relative to at least one of the sheet supplying and sheet removing means. The adjusting means can be located at the converting station. If the conveyor comprises an endless flexible element, the adjusting means for such conveyor can comprise a roller which engages the endless flexible element and is movable relative to at least one of the sheet supplying and sheet removing means. One side of the flexible element can confront the deflecting means, the supplying means and the removing means, and the other side of such flexible element can be contacted by the adjusting means. The supplying means can comprise a first pulley at the converting station, the removing means can comprise a second pulley at the converting station, and the directing means can be disposed between the two pulleys and can confront the roller of the adjusting means for the conveyor.
Another feature of the invention resides in the provision of a method of delivering successive flexible sheets of a file of non-overlapping sheets in a predetermined direction along a first path wherein a trailing section of each preceding sheet is located ahead of a leading section of the next-following sheet to a scalloping or converting station where the trailing sections of preceding sheets are caused to overlap with the leading sections of the respective next-following sheets. The improved method comprises the steps of supplying successive sheets of the file in the predetermined direction along a first path to the converting station at a first speed, removing successive sheets of the file from the converting station along a second path at a different second speed less than the first speed so that the leading sections of sheets arriving at the converting station overlap with the trailing sections of the respective preceding sheets, deflecting at the converting stationxe2x80x94with a variable forcexe2x80x94at least one of each pair of neighboring sections including the trailing section of a preceding sheet and the leading section of the respective next-following sheet so that the sections of the pairs come to overlap with each other as a result of the difference between the first and second speeds, and varying the aforementioned force as a function of at least one of a plurality of variable parameters including the first and second speeds, the flexibility, moisture content and specific weight of sheets, the temperature at the first path and/or at the converting station, the dimensions of the leading and/or trailing sections of the sheets, and the orientation of the first and second paths relative to each other.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, bot as to its construction and the modes of assembling and operating the same, together with numerous additional important advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.